Don Chadwick studied industrial design at the University of California Los Angeles until 1959. From 1964 he had his own design practice. Don Chadwick began to collaborate with Hermann Miller, a furniture-making company, in the mid-1970s. At that time Bill Stumpf was assistant director of the research division. In 1974 Don Chadwick designed "Modular Seating", a system for upholstered seat furniture. It consists of five independent modules, one of which is rectangular while the other four are wedge-shaped. Any number of these modules can be fitted together to make an endless sofa. The collaboration between Don Chadwick and Bill Stumpf worked especially well for the development of office chairs. "Ergon" (1970-76), an office chair they developed jointly, set new standards of ergonomic seating. Bill Stumpf left Hermann Miller in 1974 and in 1977 he and Don Chadwick founded Chadwick, Stumpf & Associates, a design agency, in Winona, Minnesota. They continued to develop highly innovative office chairs for Hermann Miller. The 1984 "Equa" chair represented a further development of "Ergon" with a flexible back for even more comfortable sitting. In 1992 Don Chadwick and Bill Stumpf launched "Aeron", an office chair with a seat and back of breathable polyester. Since the chair did not need separate upholstery, production time was considerably reduced. The "Aeron" fulfilled ergonomic, functional, and economic criteria, setting the standard for progressive office furniture design in the 1980s.